Author
Martin Gazvoda
Bio: Martin Gazvoda is an academic researcher from University of Ljubljana. The author has contributed to research in topics: Catalysis & Medicine. The author has an hindex of 11, co-authored 29 publications receiving 436 citations.
Topics: Catalysis, Medicine, Mitsunobu reaction, Reagent, Palladium
Papers
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TL;DR: Experimental and theoretical support is provided for two interlinked palladium cycles operating in the debated Sonogashira coupling mechanism.
Abstract: The seminal contributions by Sonogashira, Cassar and Heck in mid 1970s on Pd/Cu- and Pd-catalysed (copper-free) coupling of acetylenes with aryl or vinyl halides have evolved in myriad applications. Despite the enormous success both in academia and in industry, however, critical mechanistic questions of this cross-coupling process remain unresolved. In this study, experimental evidence and computational support is provided for the mechanism of copper-free Sonogashira cross-coupling reaction. In contrast to the consensus monometallic mechanism, the revealed pathway proceeds through a tandem Pd/Pd cycle linked via a multistep transmetallation process. This cycle is virtually identical to the Pd/Cu tandem mechanism of copper co-catalysed Sonogashira cross-couplings, but the role of CuI is played by a set of PdII species. Phosphine dissociation from the square-planar reactants to form transient three-coordinate Pd species initiates transmetallation and represents the rate-determining step of the process.
70 citations
TL;DR: In this paper, N-heterocyclic carbene precursors for bidentate coordination to ruthenium(II) through the CNHC and Npyridyl donors were investigated.
70 citations
TL;DR: Catalytic Mitsunobu reactions have been substantially improved based on strict optimization, mechanistic studies and discovery of a new catalyst.
Abstract: Ethyl 2-arylhydrazinecarboxylates can work as organocatalysts for Mitsunobu reactions because they provide ethyl 2-arylazocarboxylates through aerobic oxidation with a catalytic amount of iron phthalocyanine. First, ethyl 2-(3,4-dichlorophenyl)hydrazinecarboxylate has been identified as a potent catalyst, and the reactivity of the catalytic Mitsunobu reaction was improved through strict optimization of the reaction conditions. Investigation of the catalytic properties of ethyl 2-arylhydrazinecarboxylates and the corresponding azo forms led us to the discovery of a new catalyst, ethyl 2-(4-cyanophenyl)hydrazinecarboxylates, which expanded the scope of substrates. The mechanistic study of the Mitsunobu reaction with these new reagents strongly suggested the formation of betaine intermediates as in typical Mitsunobu reactions. The use of atmospheric oxygen as a sacrificial oxidative agent along with the iron catalyst is convenient and safe from the viewpoint of green chemistry. In addition, thermal analysis of the developed Mitsunobu reagents supports sufficient thermal stability compared with typical azo reagents such as diethyl azodicarboxylate (DEAD). The catalytic system realizes a substantial improvement of the Mitsunobu reaction and will be applicable to practical synthesis.
64 citations
TL;DR: A novel bis(pyridyl-functionalized 1,2,3-triazol-5-ylidene)-palladium(II) complex catalyses the copper-, amine-, phosphine-, and additive-free aerobic Sonogashira alkynylation of (hetero)aryl bromides in water as the only reaction solvent.
58 citations
TL;DR: An investigation of the recently reported "fully catalytic Mitsunobu reaction" using catalytic amounts of a phosphine reagent and an azo reagent has shown that although benzyl 4-nitrobenzoate is formed under the fully catalytic conditions, the same result is obtained if the hydrazine catalyst is omitted, indicating that this is not a MitsunOBu reaction.
45 citations
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TL;DR: This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives and their synthesis and biological activity.
340 citations
TL;DR: Mesoionic carbenes as discussed by the authors are a subclass of the family of N-heterocyclic Carbenes that generally feature less heteroatom stabilization of the carbenic carbon and hence impart specific donor properties and
Abstract: Mesoionic carbenes are a subclass of the family of N-heterocyclic carbenes that generally feature less heteroatom stabilization of the carbenic carbon and hence impart specific donor properties and
316 citations
01 Jan 2004
TL;DR: Mononuclear palladium-allyl complexes bearing one N-heterocyclic carbene (NHC) ligand have been synthesized in this article, which offer a straightforward entryway into a number of catalytic cycles by simple action of a base.
Abstract: Mononuclear palladium-allyl complexes bearing one N-heterocyclic carbene (NHC) ligand have been synthesized. These complexes offer a straightforward entryway into a number of catalytic cycles by simple action of a base.
241 citations
TL;DR: Recent advances made towards the discovery anti-TB agents holding INH as a nucleus including INH hybrids and INH hydrazide-hydrazone derivatives are summarized.
158 citations
TL;DR: This review will highlight the reported examples of reactions that make use of two simultaneous catalytic cycles driven by two transition metal catalysts.
Abstract: Synergistic catalysis, a type of plural catalysis which utilizes at least two different catalysts to enable a reaction between two separately activated substrates, has unlocked a plethora of previously unattainable transformations and novel chemical reactivity. Despite the appreciable utility of synergistic catalysis, specific examples involving two transition metals have been limited, as ensuring a judicious choice of reaction parameters to prevent deactivation of catalysts, undesirable monocatalytic event(s) leading to side products, or premature termination and other potentially troublesome outcomes present a formidable challenge. Excluding those driven by photocatalytic mechanisms, this review will highlight the reported examples of reactions that make use of two simultaneous catalytic cycles driven by two transition metal catalysts.
154 citations